Semiconductor device and method for manufacturing the same

ABSTRACT

The present invention provides a semiconductor device formed over an insulating substrate, typically a semiconductor device having a structure in which mounting strength to a wiring board can be increased in an optical sensor, a solar battery, or a circuit using a TFT, and which can make it mount on a wiring board with high density, and further a method for manufacturing the same. According to the present invention, in a semiconductor device, a semiconductor element is formed on an insulating substrate, a concave portion is formed on a side face of the semiconductor device, and a conductive film electrically connected to the semiconductor element is formed in the concave portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device that is thin andlightweight, and a method for manufacturing the same.

2. Description of the Related Art

In recent yeas, cellular phones spread with progress of communicationtechnology. Furthermore, more moving images and more information aregreatly expected to be sent in the future. On the other hand, personalcomputers for mobile are produced by virtue of the weight saving. Alarge number of portable information terminal such as PDA (personaldigital assistants), which begin from an electronic notebook, areproduced, and are being widely used. Moreover, most of such portableinformation devices are each equipped with a flat panel display with thedevelopment in display devices.

In such a display device, brightness in the periphery of the displaydevice is detected, and its display brightness is adjusted. Thus,needless electric power consumption can be eliminated by detectingbrightness in the periphery and obtaining moderate display brightness.For example, such an optical sensor device for brightness control isused for cellular phones and personal computers (for example, Reference1: Japanese Patent Laid Open No. 2003-60744).

As a material of an optical sensor, a semiconductor is mainly used, andsilicon is given as a representative example of the semiconductormaterial. As optical sensors using silicon, there are an optical sensorusing single crystal silicon or polysilicon and an optical sensor usingamorphous silicon. As for the optical sensor using single crystalsilicon or polysilicon, sensitivity is highest in the infrared region ofapproximately 800 nm, and has sensitivity even at approximately 1100 nm.Therefore, in the case of sensing white fluorescent light that hardlyinclude a spectrum of the infrared region and sunlight having a widespectrum from the ultraviolet region to the infrared region, there is aproblem that sensing results of each light are different while actualilluminance thereof are equal.

Further, the optical sensor using single crystal silicon is used as aresin sealing package using a lead frame for mounting on a wiring boardor the like, or a package in which a single crystal silicon is mountedon a resin substrate provided with a circuit pattern by a wire bondingmethod or a face down method.

On the other hand, the optical sensor using amorphous silicon hardly hassensitivity against light in the infrared region, and has the highestsensitivity in a range of about 500 nm to 600 nm that is a center ofwavelength of the visible light region. That is, the optical sensorusing amorphous silicon has sensing characteristics that are similar tohuman visibility. Therefore, the optical sensor using amorphous siliconis preferable.

On the other hand, a light-transmitting plastic substrate is preferablyused instead of a glass substrate. This is because a plastic substrateis thinner and lighter than a glass substrate, and a wiring boardmounting them and electronic devices using it can be also thinner andsmaller. Further, this is because a plastic substrate is flexible andcan be set on a curved surface. Moreover, an element that can resist animpact can be provided by using a plastic substrate having flexibility.

However, since a plastic substrate is thin, a connection terminal cannotbe formed on a side face of a substrate. Therefore, a connectionterminal is formed on one surface of the substrate so as to a wiringboard. A wiring board and an optical sensor are fixed by only onesurface with a solder, and its area for bonding is small. Thus, there isa problem that mounting strength is weak as compared with a sideelectrode structure since the bonding area is small.

In addition, it is difficult to see a connection portion of an electrodeof the optical sensor and an electrode terminal and to judge whetherthese connects to each other surely, because a region where the wiringboard is connected to the optical sensor is in the lower part of asubstrate of the optical sensor.

In addition, since some conventional organic resin materials or plasticsubstrates have poor heat-resistance, they cannot be mounted on a wiringboard by a reflow step using solders.

Further, the optical sensor using single crystal silicon has a packagingstructure, in which a wiring region for mounting an optical sensor (forexample, regions provided with a lead frame and a circuit pattern) islarger than an area for functioning as an optical sensor. Accordingly,such a packaging structure of an optical sensor is interfering with highintegration on a wiring board.

SUMMARY OF THE INVENTION

In view of the above described problems, it is an object of the presentinvention to provide a semiconductor device formed over an insulatingsubstrate, typically an optical sensor, a solar battery, or a circuitusing a TFT, a semiconductor device having a structure in which mountingstrength to a wiring board can be increased and which can make it mounton a wiring board with high density, and further provide a method formanufacturing the same.

One feature of the present invention is a semiconductor device in whicha semiconductor element is formed on an insulating substrate, a concaveportion is formed on a side face of the semiconductor device, and aconductive film electrically connected to the semiconductor element isformed in the concave portion.

Another feature of the present invention is a semiconductor devicehaving a semiconductor element formed on an insulating substrate, anelectrode terminal to be connected with the semiconductor element, and aconnection terminal to be connected to the electrode terminal, wherein aconcave portion is formed in side faces of the insulating substrate andthe semiconductor element, and the connection terminal covers theinsulating substrate and the semiconductor element in the concaveportion.

Another feature of the present invention is a semiconductor devicehaving a concave portion in a side face thereof, which comprises asemiconductor element formed over an insulating substrate, an insulatingfilm covering the semiconductor element, and a conductive film to beelectrically connected to the semiconductor element, wherein theconductive film is formed in the concave portion and covers the sidefaces of the insulating substrate and insulating film.

One feature of the present invention is a semiconductor device having aconcave portion in a side face thereof, includes a semiconductor elementformed on an insulating substrate, an electrode terminal to be connectedto the semiconductor element, an insulating film covering thesemiconductor element and the electrode terminal, and a connectionterminal to be connected to the electrode terminal through theinsulating film, wherein the connection terminal is in contact with sidefaces of the insulating substrate, the semiconductor element, and theinsulating film in the concave portion.

The area of the insulating substrate and the area for forming thesemiconductor element are almost equal according to the presentinvention.

A substrate that has heat resistance enough to resist in a mounting stepon a board for mounting is preferably used for the insulating substrate.A substrate having a glass transition temperature of 260° C. or more isfurther preferable. A light-transmitting substrate is also preferable.As a typical example, a plastic substrate, a glass substrate, and asubstrate made of organic resin are cited.

The above-mentioned conductive film is a connection terminal. Theconnection terminal is a terminal for electrically connecting asubstrate to mount a semiconductor device, e.g., an electrode terminalformed on a wiring board, and a semiconductor element of thesemiconductor device. The connection terminal is electrically connectedto the electrode terminal on the wiring board by a conductive paste, ananisotropic conductive adhesive agent, an anisotropic conductive film orthe like and they are fixed.

The above-mentioned concave portion is semicylinder like or rectangularcolumn like, and has a curved surface or a flat surface. Further, theconcave portion may be a shape having a curved surface and a flatsurface.

The semiconductor element is an element in which an active region ismade of a semiconductor thin film, and is typified by a diode, a TFT, acapacitor element and the like. In addition, the semiconductor thin filmis formed from an inorganic material or an organic material.

For a representative example of a semiconductor film formed from aninorganic material, a silicon film, a gallium film, a silicon film addedwith gallium, a silicon carbide film and the like can be given. Inaddition, a representative example of a semiconductor film formed froman organic material includes polymer or oligomer represented byconjugated polymer, for example, a polyphenylenevinylene derivative, apolyfluorene derivative, a polythiophene derivative, a polyphenylenederivative and a copolymer thereof such as oligophenylene, andoligothiophene. Further, pentacene, tetracene, copper phthalocyanine,perfluorinated phthalocyanine, a perylene derivative and the like aregiven for an example of a low molecular substance.

In the present invention, when the semiconductor device is an opticalsensor, a photoelectric conversion device, a solar battery, asemiconductor film is formed from a film comprising silicon. For arepresentative example of the semiconductor film having silicon, asilicon film, a silicon germanium film, a silicon carbide film and a PNjunction film or a PIN junction film thereof are given. It is desirablethat I layers of the PIN junction film are formed from an amorphoussilicon layer.

In addition, an amplifier circuit or an amplifier element may beprovided in the light-receiving portion for amplifying a detectionamount of light received in a light-receiving portion. A current mirrorcircuit formed from a TFT is given for a representative example of theamplifier circuit, and an operation amplifier (op-amp) is given for arepresentative example of the amplifier element.

Moreover, as the semiconductor device of the present invention, anintegrated circuit which is formed by using an optical sensor, aphotoelectric conversion device, or a solar battery, and which includesa TFT, a capacitor element or the like, is given. In addition, afunctional circuit such as a memory or a CPU is cited as the integratedcircuit using a TFT.

Also, the present invention relates to a method for manufacturing asemiconductor device, wherein a plurality of semiconductor elements areformed over the insulating substrate, an opening portion is formed at adesired portion of the substrate, a conductive film electricallyconnected to the semiconductor element is formed in the opening portion,and then, the semiconductor elements are cut out to form chip-likesemiconductor devices.

As the method for forming the opening portion, a laser irradiationmethod, an etching method, a method of pressing with a mold and the likeare given.

The semiconductor device of the present invention has a concave portionin a side face of an insulating substrate, and a connection terminal canbe formed in the portion. In other words, a semiconductor device havinga side electrode can be formed. Thus, an area for connection with awiring board can be increased, the mounting strength is also increased,and at the same time, the condition of connection can be seen andconfirmed visibly. Accordingly, reliability on process can be enhanced.Also, since a connection terminal can be formed by forming an openingportion in the substrate and forming a conductive film along the openingportion, connection terminals for a plurality of semiconductor devicecan be provided on one substrate. Therefore, it is possible to form aplurality of semiconductors device by using one substrate, to increasethroughput in the step of forming a connection terminal, and tomass-produce. Moreover, a semiconductor element is formed over asubstrate, and the area of the substrate and the area of an effectiveregion needed for functioning as the semiconductor element are almostequal. Thus, a large number of semiconductor elements can be integratedhighly on a wiring board or the like. These and other objects, featuresand advantages of the present invention become more apparent uponreading of the following detailed description along with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A and 1B each show an oblique drawing and a cross sectional viewof a semiconductor device of the present invention;

FIGS. 2A and 2B each show an oblique drawing and a cross sectional viewof a semiconductor device of the present invention;

FIG. 3 shows a driver circuit of a semiconductor device of the presentinvention;

FIGS. 4A to 4D each show a manufacturing step of a semiconductor deviceof the present invention;

FIGS. 5A and 5B each show a top view and a cross sectional view in whicha semiconductor device of the present invention is mounted on a wiringboard;

FIGS. 6A to 6D each show a step of manufacturing a semiconductor deviceof the present invention;

FIGS. 7A to 7D each show a step of manufacturing a semiconductor deviceof the present invention;

FIGS. 8A to 8D each show a step of manufacturing a semiconductor deviceof the present invention;

FIGS. 9A and 9B each show an oblique drawing and a cross sectional viewof a semiconductor device of the present invention

FIGS. 10A to 10C each show a cross sectional view of a semiconductordevice of the present invention; and

FIGS. 11A and 11B each show a cross sectional view of a semiconductordevice of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiment modes of the present invention are describedwith reference to the accompanying drawings. The present invention canbe implemented in various different modes. It will be obvious to thoseskilled in the art that various changes may be made without departingfrom the scope of the present invention. Therefore, the presentinvention should not be limited to the embodiment modes. Hereinafter, anoptical sensor is described as a representative example of semiconductordevices, but the present invention is not limited thereto, and can beapplied to an integrated circuit formed by using a photoelectricconversion device, a solar battery, a TFT, and/or the like. A plasticsubstrate is used as an insulating substrate, but the present inventionis not limited thereto. A glass substrate, a substrate made of organicresin or the like can be employed.

Embodiment Mode 1

An optical sensor that is formed over a plastic substrate and that has aconcave portion in a side face thereof is described with reference toFIGS. 1A and 1B in this embodiment mode.

FIG. 1A is an oblique drawing of an optical sensor 100 of the presentinvention. A semiconductor element 102 is formed over a plasticsubstrate 101. A side face of the optical sensor 100 has a concaveshape, and a conductive film to be connection terminals 103 a and 103 bis formed in this area.

The semiconductor element 102 can be integrally formed on the substrateby using a semiconductor film, preferably, a semiconductor thin film,and thus, downsizing and thinning of a semiconductor device can beachieved.

The concave shape in the side face of the optical sensor is curved inthis embodiment mode. Note that the concave shape may have a flatsurface. That is to say, the concave shape is a semi cylindrical havinga curved surface or a rectangular column having a flat surface.

Further, the concave portion may have a shape having both a curvedsurface and a flat surface.

Next, FIG. 1B shows a cross-sectional view taken along the line (A)-(A′)of FIG. 1A. The semiconductor element 102 is formed over the plasticsubstrate 101. The semiconductor element 102 includes a first electrode111, a light-receiving portion 112, and a second electrode 113. A firstelectrode terminal 114 is connected to the first electrode 111 and asecond electrode terminal 115 is connected to the second electrode 113.In addition, the first electrode terminal 114 is electrically insulatedfrom the second electrode 115 with an interlayer insulating film 116interposed therebetween. The first connection terminal 103 a isconnected to the first electrode terminal 114 and the second connectionterminal 103 b is connected to the second electrode terminal 115. Eachof the first connection terminal 103 a and the second connectionterminal 103 b is a terminal for connecting to an electrode terminal ona wiring board.

As the plastic substrate, a substrate that can resist heat in the stepof mounting on the wiring board (typically, a substrate havingglass-transition temperature of 260° C. or more) is preferable. Further,a substrate comprising an organic material dispersed with inorganicparticles of several nm in diameter is also given as a representativeexample.

For a representative example of the mounting step on the wiring board,there are a reflow method using a conductive adhesive agent such assolder, a pressure-bonding method using an anisotropic conductiveadhesive agent, and the like. When the pressure-bonding method isemployed, a plastic substrate that is poor in heat resistance can beused, since it is mounted on a wiring board using an anisotropicconductive adhesive agent or an anisotropic conductive film.

A substrate having a certain degree thickness is preferably used for theplastic substrate, in order to increase the junction area.Representatively, a plastic substrate (plate) that is 100 to 1000 μmthick, preferably 20 to 500 μm thick, is preferable.

Polycarbonate (PC), ARTON made of norbornene resin including a polargroup, which is manufactured by JSR corporation, polyethyleneterephthalate (PET), polyether sulfone (PES), polyethylene naphthalate(PEN), nylon, polyetheretherketone (PEEK), polysulfone (PSF),polyetherimide (PEI), polyarylate (PAR), polybutylene telephthalate(PBT), polyimide, a HT substrate made of an organic material dispersedwith inorganic particles of several nm in diameter, which ismanufactured by Nippon Steel Corporation, and the like can be given as arepresentative example of the plastic substrate.

When light enters from the plastic substrate 101 side, the firstelectrode 111 is made of a light-transmitting conductive film that canhave an ohmic contact with a semiconductor film made of silicon. An ITO(indium-tin oxide alloy), an indium zinc alloy (In₂O₃—ZnO), an zincoxide (ZnO), indium-tin oxide including silicon oxide can be used,typically. The second electrode 113 is formed from a metal film that canhave an ohmic contact with the semiconductor film made of silicon. It isformed from one element selected from aluminum (Al), titanium (Ti),chrome (Cr), nickel (Ni), molybdenum (Mo), palladium (Pd), tantalum(Ta), tungsten (W), platinum (Pt), gold (Au) or an alloy materialcontaining 50% or more of the element, representatively. On the otherhand, when light enters from the interlayer insulating film 116 side,the first electrode 111 is made of a metal film that can have an ohmiccontact with a semiconductor film made of silicon, and the secondelectrode 113 is made of a light-transmitting conductive film that canhave an ohmic contact with the semiconductor film made of silicon.

The light-receiving portion 112 can be formed from a semiconductor layerhaving silicon. A silicon layer, a silicon germanium layer, a siliconcarbide layer and a PN junction layer or a PIN junction layer thereofare given for a representative example thereof. In this embodiment mode,the light-receiving portion 112 is formed from amorphous silicon with aPIN junction.

Each of the first electrode terminal 114 and the second electrodeterminal 115 is a leading-out electrode, and a terminal for electricallyconnecting each of the first and second electrodes 111 and 113 toelectrodes terminals formed on the wiring board. Accordingly, the firstand second electrode terminals 114 and 115 are formed from a medium forconnecting the first and second electrodes and wirings, for example, aconductive paste containing one or plural elements selected from silver,gold, copper, platinum, palladium, tin and zinc, or a material that canbe connected to a solder paste or the like. Nickel (Ni), copper (Cu),zinc (Zn), palladium (Pd), silver (Ag), tin (Sn), platinum (Pt) or gold(Au), and preferably, one element chosen from nickel (Ni), copper (Cu),silver (Ag), platinum (Pt) and gold (Au), or an alloy materialcontaining 50% or more of the element are given as a representativeexample. Note that the first and second electrode terminals 114 and 115may have a single layer structure or a multilayer structure.

The first and second connection terminals 103 a and 103 b are formed inthe concave portions in the side faces of the substrate and portions ona surface of the optical sensor. The connection terminals are eachconnected to respective electrode terminals. The connection terminalscomprise a conductive paste containing one or plural elements selectedfrom silver, gold, copper, platinum, palladium, tin and zinc or amaterial that can be bonded to a solder paste. Nickel (Ni), copper (Cu),zinc (Zn), palladium (Pd), silver (Ag), tin (Sn), platinum (Pt) or gold(Au), and preferably, one element selected from nickel (Ni), copper(Cu), silver (Ag), platinum (Pt) and gold (Au), or an alloy materialcontaining 50% or more of the element are given as a representativeexample. Note that the metals are not necessarily a single composition(one element), but may be an alloy composition including it. Note thatthe alloy is an alloy including 50% or more of the metal as the maincomponent. Note that the first electrode terminal 114 and the secondelectrode terminal 115 may have a single layer structure or a multilayerstructure.

The interlayer insulating film 116 is formed to electrically insulatethe electrode terminals 114 and 115 serving as the leading-outelectrodes, as well as sealing respective electrodes 111 and 113, andthe semiconductor element 102, and suppressing deterioration. Theinterlayer insulating film 116 can be formed from organic resin such asacryl, polyimide, polyamide, polyimidamide, or benzocyclobutene or aninorganic material such as a silicon oxide film, a silicon nitride oxidefilm or a silicon oxynitride film.

It is preferable that side faces of the optical sensor are sloping onwhich a conductive film to be connection terminals is formed. Astructure at this time is shown in FIGS. 9A and 9B. FIG. 9A is anoblique drawing of an optical sensor 120. FIG. 9B shows across-sectional view taken along the line (E)-(E′) of FIG. 9A. The sidefaces of an interlayer insulating film 125 and a substrate 121 haveslopes, and connection terminals 123 a and 123 b are formed thereon,respectively. In the structure, when the conductive film is formed in avapor phase of a vapor deposition method, a sputtering method or thelike, the coverage of the conductive film can be enhanced anddisconnection between films can be prevented. Note that the shape of theside faces of the substrate is not limited thereto, but may have a steplike shape or a convex curved surface in the outside.

A structure of the semiconductor element of the optical sensor canemploy other structures than the structure shown by the cross-sectionalview in FIG. 1B. A cross-sectional view of an optical sensor having adifferent semiconductor element structure is shown in FIGS. 11A and 11B.

FIG. 11A is an example of a cross-sectional view of an optical sensor,which is formed from a light-receiving portion 112, a first electrodeterminal 114 contacting with the light-receiving portion 112, a secondelectrode 113, a second electrode terminal 115 connected to the secondelectrode 113, and connection terminals 103 a and 103 b connected to theelectrode terminals 114 and 115. A first electrode is not provided inFIG. 11A, which is different from the optical sensor in FIG. 1B.Accordingly, the number of connection portions (contact portion) ispreferably large, since the reliability of the device is enhanced byincreasing the area in which the first electrode terminal 114 is incontact with the light-receiving portion 112. In this structure, it ispossible to reduce the number of processes and increase transmittance oflight that is transmitted from the substrate 101, since the firstelectrode is not provided.

FIG. 11B is an example of a cross sectional view of an optical sensor,which is formed from a light-receiving portion 132, a first electrodeterminal 114 contacting with the light-receiving portion 132, a secondelectrode 113, a second electrode terminal 115 connected to the secondelectrode, and connection terminals 103 a and 103 b connected to theelectrode terminals 114 and 115. A layer of the light-receiving portion132 is not patterned and is formed over the entire surface of thesubstrate 101, which is different from the optical sensor in FIG. 11A.Accordingly, a light-receiving portion can be formed without using amask, and thus, an alignment control for the mask is not required.Therefore, yield can be improved.

According to the present invention, a semiconductor device can be formedover an insulating substrate. The semiconductor device of the presentinvention has a concave portion in a side face thereof, and a connectionterminal can be formed in this area. A connection with an electrodeterminal on a wiring board is made by a connection terminal and anelectrode terminal. Thus, an area for connection with a wiring board canbe increased, the mounting strength can be also increased, and at thesame time, the condition of connection can be seen and confirmedvisibly. Accordingly, reliability on process can be enhanced.

Embodiment Mode 2

An optical sensor having a circuit for amplifying current detected in alight-receiving portion is described with reference to FIGS. 2A and 2B.An example of using a thin film transistor (hereinafter, referred to asa TFT) as an element constituting an amplifier circuit is shown, but thepresent invention is not limited thereto and can employ an operationalamplifier (op-amp) and the like.

FIG. 2A is an oblique drawing of an optical sensor of this embodimentmode. As in Embodiment Mode 1, a semiconductor element 202 is formed ona surface of a plastic substrate 101. A diode or a TFT having such astructure shown in Embodiment Mode 1 can be appropriately applied to thesemiconductor element. In addition, a side face of an optical sensor 200has a concave portion, and a conductive film to be connection terminals103 a and 103 b is formed therein. The shape shown in Embodiment Mode 1can be applied to the shape of the concave portion in the side face ofthe optical sensor.

FIG. 2B is a cross-sectional view taken along the line (B)-(B′) of FIG.2A. A first insulating film 211 is formed over a plastic substrate 101and a TFT 212 is formed thereon. The TFT 212 includes a semiconductorregion 213 having a channel forming region, a source region and a drainregion; a gate electrode 214; a source electrode 215 connected to thesource region; and a drain electrode 216 connected to the drain region.In the TFT 212, the channel forming region, the gate electrode, thesource electrode and the drain electrode are insulated from one anotherby a plurality of insulating films 217. In this embodiment mode, ann-channel TFT is used for the TFT 212. Only one TFT is shown in FIG. 2B,but plural TFTs can be formed.

The semiconductor region of the TFT 212 can be formed by using anamorphous semiconductor film, a crystalline semiconductor film or amicrocrystal semiconductor film. The amorphous semiconductor film can beformed by plasma CVD, low pressure CVD or sputtering. The crystallinesemiconductor film is formed by the above-mentioned method and then, itcan be crystallized by a laser crystallization method, a crystallizationmethod by heating, or a method disclosed in Japanese Patent Laid OpenNo. H8-78329. According to the technique of the gazette, a metal elementfor promoting crystallization is selectively added into an amorphoussilicon film, and heat-treated to expand the element from the addedregion that is a starting point, thereby forming a semiconductor filmhaving a crystal structure. Note that it is preferable to remove themetal element after crystallization in this treatment.

The microcrystal semiconductor film has an intermediate structurebetween an amorphous structure and a crystal structure (including asingle crystal, and polycrystal), the third state that is stable in freeenergy, and includes a crystalline region having a short distance orderand lattice distortion. A crystal grain of 0.5 to 20 nm is included atleast in a certain region in a film.

The microcrystalline semiconductor film is formed by performing glowdischarging decomposition (plasma CVD) on a silicide gas. As thesilicide gas, SiH₄, Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄, SiF₄, and the likecan be used. The silicide gas may be diluted with H₂, or H₂ and one ormore of rare gas elements: He, Ar, Kr, and Ne. Dilution ratio is withinthe range of from twice to 1000 times. At this time, the pressure isroughly within the range of from 0.1 Pa to 133 Pa; power frequency isfrom 1 MHz to 120 MHz, preferably from 13 MHz to 60 MHz; and substrateheating temperature is at most 300° C., preferably from 100° C. to 250°C. An atmospheric constitution impurity such as oxygen, nitrogen, orcarbon as an impurity element within a film is preferably at most1×10²⁰/cm³ or less, in particular, oxygen concentration is at most5×10¹⁹/cm³ or less, preferably, at most 1×10¹⁹/cm³ or less.

A first electrode 111, a light-receiving portion 112, a second electrode113, and an interlayer insulating film 218 are laminated sequentiallyover the insulating films 217. A structure and a material for them canbe appropriately adapted from those described in Embodiment Mode 1.

Here, a connection of a first electrode and a drain electrode that areeach formed on the insulating films 217, of a light-receiving portion,is described with reference to FIGS. 10A to 10C.

FIG. 10A shows a wiring (a drain electrode) 1301, a first electrode 1302connected to the wiring 1301, a light-receiving portion 1303 formed onthe first electrode 1302, and a second electrode 1304 formed on thelight-receiving portion 1303. In this structure, a whole face of oneside of the light-receiving portion 1303 is in contact with the firstelectrode 1302. Further, the adhesiveness of the insulating films 217and the first electrode 1302 is increased, and thus, a film-peeling thatoccurs between the light-receiving portion 1303 and the insulating films217 can be prevented in this structure.

FIG. 10B shows a wiring (drain electrode) 1311, a light-receivingportion 1313 covering a portion of the wiring 1311, and the secondelectrode 1314. In this structure, the wiring 1311 serves also as thefirst electrode 1302 in FIG. 10A. Further, in this structure, it ispossible to reduce the number of processes and increase transmittance oflight that is transmitted from the insulating films 217, since the firstelectrode is not provided.

FIG. 10C shows a wiring (a drain electrode) 1321, a first electrode 1322connected to the wiring 1321, a light-receiving portion 1323 covering aportion of the first electrode 1322 and the insulating films 217, and asecond electrode 1324. In this structure, the area of the firstelectrode is small, and a portion of the light-receiving portion is incontact with the insulating films 217. Accordingly, there is an effectthat the transmittance of light transmitted from the interlayerinsulating film 217 is increased.

Then, as shown in FIG. 2B, a first electrode terminal 114 is connectedto a source electrode of a TFT 212, and a second electrode terminal 115is connected to a second electrode 113 of a light-receiving portion 112.A first connection terminal 103 a is connected to the first electrodeterminal 114, and a second connection terminal 103 b is connected to thesecond electrode terminal 115. The first connection terminal 103 a andthe second connection terminal 103 b are terminals for connecting towirings on a wiring board. As for these materials, materials shown inEmbodiment Mode 1 can be employed, similarly.

In this embodiment mode, a top gate type TFT is shown as the TFT, butthe TFT is not limited thereto and may be a bottom gate type TFT, aninversely staggered TFT or the like.

According to the present invention, a semiconductor device can be formedon an insulating substrate. A semiconductor device of this embodimentmode is an optical sensor having an amplifier circuit. Accordingly,feeble light can be also detected. Even when the area for receivinglight of the optical sensor is small, high output can be obtained. Aconcave portion is formed on a side face of the optical sensor, and aconnection terminal can be formed in this region. Thus, an area forconnection with a wiring board can be increased, the mounting strengthis also increased, and at the same time, the condition of connection canbe seen and confirmed visibly. Accordingly, reliability on process canbe enhanced.

Embodiment Mode 3

An example of a driver circuit of an optical sensor in Embodiment Mode 2is shown with reference to FIG. 3. In this embodiment mode, a currentmirror circuit is used as an amplifier circuit in the optical sensor.

Herein, two transistors are connected to each other and one of them isconnected to a diode (a light-receiving portion). The TFT connected to adiode 301 is a first TFT 302, and the TFT that is connected to the firstTFT in parallel is a second TFT 303. Gate electrodes and source wiringsof the first TFT 302 and the second TFT 303 are connected to oneanother. A drain of the first TFT 302 is connected to a cathode of thediode 301, and an anode of the diode 301 is connected to a drain of thesecond TFT 303. Sources of the first TFT and the second TFT areconnected to V_(SS) 304. The anode of the diode and the drain of thesecond TFT are connected to V_(DD) 305 that is an output terminal, andbrightness of light can be detected by a value of current flowing at thepoint.

When light enters the diode 301, light current flows from the anode tothe cathode in the diode 301. Thus, current I₁ flows between the sourceand the drain of the first TFT 302. Voltage V₁ is generated between thesource and drain of the first TFT 302, since the drain of the first TFT302 is connected to the gate electrode thereof. Voltage V₂ is generatedbetween the source and the drain of the second TFT 303. The sources andthe gates of the first TFT 302 and the second TFT 303 are connected toone another. When the first TFT 302 and the second TFT 303 are driven ina linear region, current at the voltage V₁ and the voltage V₂ canapproximate current I₁. Accordingly, current I₁ flows between the sourceand the drain of the second TFT 303, too. The two TFTs 302 and 303 areconnected to each other in parallel, and thus, current 211 flows in theoutput terminal 305.

The first TFT 302 converts current, which is generated when the diode301 is irradiated with light, into voltage, and the second TFT 303amplifies the current generated in the diode 301 through the first TFT302. Note that the current generated in the diode can be more amplifiedby connecting plural TFTs for amplifying in parallel. In other words,when n TFTs for amplifying are connected in parallel with the first TFT302, (1+n) times current as much as the current generated in the diode301 flows in the output terminal 305.

In addition, it is also effective to increase a W/L ratio of the secondTFT so as to amplify current generated in the diode which is a currentsource. Specifically, the current generated in the current source can beamplified and detected, since current flowing in the second TFTincreases by increasing the channel width (W) of the second TFT ordecreasing the channel length (L) thereof.

In this embodiment mode, the optical sensor using the current mirrorcircuit is shown, but the present invention is not limited thereto. Forexample, instead of the current mirror circuit, an operational amplifieror the like can be employed.

According to the present invention, a semiconductor device can be formedon an insulating substrate. Because the connection terminal has twoterminals in the semiconductor device of this embodiment mode, thenumber of pins and the mounting area can be reduced. In addition, feeblelight can be detected, since an amplifier circuit is provided. Even whenthe area of the light-receiving portion of the optical sensor is small,high output can be obtained. Further, a concave portion is in a sideface of the optical sensor, and a connection terminal can be formed inthis region. Thus, an area for connection with a wiring board can beincreased, the mounting strength can be also increased, and at the sametime, the condition of connection can be seen and confirmed visibly.Accordingly, reliability on process can be enhanced.

Embodiment Mode 4

In this embodiment mode, a step of manufacturing an optical sensor shownin Embodiment Modes 1 to 3 is described with reference to FIGS. 4A to4D.

As shown in FIG. 4A, a semiconductor element 402 (light-receivingportion (not shown), an electrode 403 and electrode terminals 404 a and404 b) is formed on a plastic substrate 401 by a known technique. Notethat a semiconductor element can be formed on a substrate with a Roll toRoll type plasma CVD apparatus, in the case of using a flexible plasticsubstrate. Mass-production is possible by using the apparatus, and thus,cost reduction of an optical sensor can be achieved.

Then, as shown in FIG. 4B, an opening portion 411 is formed at a desiredposition of the plastic substrate by laser irradiation. The position ofthe opening portion is different depending on a structure of each sensorelement, but may be formed in a region for providing a connectionterminal. In this embodiment mode, a pair of opening portions is formedin both sides of the semiconductor element.

As shown in FIG. 4C, a conductive film 421 is formed in the openingportion 411. For the film formation method, a sputtering method, a vapordeposition method or a chemical vapor deposition using a mask, anelectrolytic plating method or the like can be employed. Next, theplastic substrate is irradiated with laser light to form a groove in theplastic substrate, thereby obtaining an optical sensor 431 shown in FIG.4D. A connection terminals 432 are formed in concave portions on sidefacea of the optical sensor 431.

A semiconductor device can be formed on an insulating substrate throughthe above described steps. Further, a concave portion is formed on aside face of the semiconductor element of the present invention, and aconnection terminal can be formed over the concave portion. Thus, anarea for connection with a wiring board can be increased, the mountingstrength is also increased, and at the same time, the condition ofconnection can be seen and confirmed visibly. Accordingly, reliabilityon process can be enhanced. Moreover, it is possible to manufacture asemiconductor device that can provide a high yield and that can realizea high density mounting on a wiring board as well as cost reduction,since a semiconductor element is formed directly on a substrate and thestep of mounting the semiconductor element on a substrate is omitted. Inaddition, by forming an opening portion in the substrate and thenforming a conductive film along the opening portion, a connectionterminal can be obtained. Thus, connection terminals of a plurality ofsemiconductor devices can be provided on one substrate. Therefore, it ispossible to increase throughput in the step of forming a connectionterminal, and to mass-produce.

Embodiment Mode 5

In this embodiment mode, a method for mounting an optical sensor formedin Embodiment Modes 1 to 4 on a wiring board is described with referenceto FIGS. 5A and 5B.

FIG. 5A is a top view in which an optical sensor is mounted on a wiringboard 1101. A semiconductor element 102 and connection terminals 103 aand 103 b are formed in the optical sensor 100. The optical sensor 100is mounted on the wiring board 1101 by conductive pastes 1102 and 1103or the like. In this embodiment mode, the semiconductor element 102 ismounted on the wiring board 1101 face to face.

FIG. 5B is a cross-sectional structure taken along the line (C)-(C′) ofFIG. 5A.

The semiconductor element 102 is formed on a plastic substrate 101. Thesemiconductor element includes a first electrode, a light-receivingportion and a second electrode. Electrode terminals 113 and 114 that areconnected to the first electrode and the second electrode, respectively,are each connected to the connection terminals 103 a and 103 b that areformed in side faces of the sensor. The connection terminals 103 a and103 b are connected to electrode terminals 1104 and 1105 on the wiringboard 1101 by the conductive pastes 1102 and 1103, respectively.

The pastes shown Embodiment Mode 1 can be used suitably for theconductive paste. In this embodiment mode, a conductive paste includingsilver is employed.

In this embodiment mode, the optical sensor 100 is mounted on the wiringboard 1101 by a reflow step. Specifically, the conductive pastes 1102and 1103 are applied to predetermined portions on the electrodeterminals 1104 and 1105 by a screen printing method or a dispenser, andthe optical sensor 100 is mounted thereon by a mounter. After that, theconductive pastes are melted by heating at temperatures from 250 to 350°C. to connect the electrode terminals 1104 and 1105 and the connectionterminals 103 a and 103 b of the optical sensor 100 with the electrodeterminals 1104 and 1105 on the wiring board 1101 electrically andmechanically.

An infrared heating method, a vapor phase soldering method, a hot-airheating method, a heating method using a hot plate, a heating method bylaser irradiation and the like are given as the heating method.

Alternatively, the optical sensor may be mounted on the wiring board bylocally pressure-bonding using an anisotropic conductive adhesive agentor an anisotropic conductive film, instead of using the method ofmounting by the reflow step using a conductive paste.

Further, the optical sensor can be mounted in the state that the wiringboard faces the plastic substrate, since the connection terminal isformed in a side face of the optical sensor, in this embodiment mode.

According to the present invention, a semiconductor device can be formedon a plastic substrate having heat resistance to a heat treatment in thestep of mounting. The optical sensor of the present invention has aconcave portion in a side face of a substrate, and a connection terminalcan be formed in this region. The connection with an electrode terminalon a wiring board is made by a connection terminal and an electrodeterminal. Thus, an area for connecting with a wiring board can beincreased, the mounting strength can be also increased, and at the sametime, the condition of connection can be seen and confirmed visibly.Accordingly, reliability on process can be enhanced.

Embodiment 1

Embodiments of the present invention are described with reference toFIGS. 6A to 6D, 7A to 7D, and 8A to 8D. FIGS. 6A, 6C, 7A, 7C, 8A and 8Care top views of substrates, and FIGS. 6B, 6D, 7B, 7D, 8B and 8D arecross sectional views taken along the line (D)-(D′) in the figures.

As shown in FIGS. 6A and 6B, a semiconductor film is formed on a plasticsubstrate 601 with a plasma CVD apparatus. Here, a silicon semiconductorfilm 602 having respective conductive type p, i, and n is formed as thesemiconductor film. Herein, the i-layer which is a light-receivingportion has amorphous phase, and phase states of p and n are notconsidered. The film thickness of the i-layer is fit in an illuminationrange of an intended element to be set to 100 to 1000 nm. In thisembodiment, an HT substrate manufactured by Nippon Steel Corporation isused as the plastic substrate, and a silicon semiconductor film isformed to have a thickness of 800 nm thereon. Note that the plasticsubstrate is 200 to 500 μm.

Then, a contact hole 603 is formed at a predetermined portion in a laserscribe step in order that a p-type silicon film that is a lower portionof the formed semiconductor film is to be connected with a metalelectrode formed in the next step, as shown in FIGS. 6C and 6D. In thisstep, the scribing is preferably performed to leave a p-typesemiconductor layer at the bottom of the contact hole, but it isdifficult to control in the depth direction by a laser and thus, thecontact hole may be formed into the surface of the plastic substrate,not to pass through it, for assuring a process margin. Accordingly, theactual contact portion between the metal electrode and the p-typesemiconductor layer is a small region, since it is equivalent to an areaof an exposed portion of the p-type semiconductor layer in the contacthole, in other word, a width of the area is equivalent to the thicknessof the p-type semiconductor layer. Thus, a large number of independentholes are formed on the substrate in order to increase the area forcontacting. Further, the energy densities of an edge and a center of abeam can be changed sequentially with a gentle slope by defocusingintentionally when it is assumed that focus control of a laser beam ispossible by using a condensing optical system. At this time, laserscribing is performed to form a taper in a wall face of a scribedportion, thereby enlarging more contact areas. In this embodiment, a YAGlaser having a wavelength of 1.06 μm and a beam diameter (φ) of 60 μm isused to scan a laser beam with an oscillation frequency of 1 kHz at arate not to be overlapped.

Then, as shown in FIGS. 7A and 7B, a first electrode 604 and a secondelectrode 605 are formed. A metal conductive film is formed to have asingle layer structure or a laminated structure as the first electrodeand the second electrode. As the film formation method, a sputteringmethod, a vapor deposition method or a plating method may be employed orthe methods are employed together. A desired electrode shape can beobtained easily by using a metal mask, in the case of using a vaporphase method such as sputtering or vapor deposition. Two openingportions for one element are formed in the metal mask, and electrodes ofthe both poles are formed simultaneously. The metal mask, the plasticsubstrate and a magnet plate are overlapped in this order, and they areset in a sputtering apparatus in the state. By completely adhering themetal mask to the plastic substrate tightly, inhomogeneous of theelectrode area due to intrusion of the deposited film therebetween isprevented. When a plating method is employed, masking is conducted onresin in advance by a screen-printing method in the region where a metalelectrode is not required, and a desired electrode shape can be obtainedby a lift-off method after forming the first electrode and the secondelectrode. The first and second electrodes 604 and 605 of 0.5 to 100 μmthick are formed under the foregoing conditions.

An Ni metal is formed by using a metal mask by a sputtering method inthis embodiment. The metal mask is 0.1 mm thick and comprises nickel.The metal mask and the plastic substrate are set in the sputteringapparatus in the state that they are adhered tightly with the magnetplate. A film made of nickel is formed by sputtering using a Ni targetof six inches in diameter with purity 99.99% and by discharging in anargon atmosphere of 1.0 Pa, with an RF output of 1.0 kW.

Then, as shown in FIGS. 7C and 7D, an insulating film 606 is formed, inwhich portions of the first electrode 604 and the second electrode 605are each exposed via contact holes. A screen-printing method is employedfor forming the insulating film. The insulating film 606 is 1.6 μmthick. Instead of the screen-printing method, an insulating film may beformed over the entire face of the substrate by a CVD method or anapplication method, and then, a portion thereof may be etched to form acontact hole for exposing each electrode. It is possible to prevent anoptical sensor from tilting when it is mounted on a wiring board, byforming the contact hole symmetrically.

Electrode terminals 607 and 608 that are leading-out electrodes areformed in the contact holes formed by exposing portions of a metalelectrode. The electrode terminals 607 and 608 can be formed from aconductive film having a metal element such as silver, gold, copper,platinum, or nickel. Each of the leading-out electrodes is formed so asto have an area of 1.35×1.8 mm² in this embodiment. A conductive filmhaving a laminated structure of titanium/nickel/gold is formed to beoverlapped with portions of the electrode terminals 607 and 608 by asputtering method using a mask in this embodiment.

As shown in FIGS. 8A and 8B, opening portions 609 are formed. Theopening portions are formed in the both sides of a region to serve as anoptical sensor, namely, outside of the two metal electrodes, by laserirradiation. As for the method of forming the opening portion, theopening portions are formed to penetrate from the insulating film 606 tothe surface of the plastic substrate 601 by laser irradiation or thelike. Under the same condition as the laser irradiation conditionemployed in forming the contact hole 603, an opening portions 609 areformed on the both sides of a minor axis of a sensor element in thisembodiment.

As shown in FIGS. 8C and 8D, conductive film that is to be connectionterminals is formed on surfaces of the opening portions 609. Theconductive film can be formed by the same method as the method forforming the first electrode 604 and the second electrode 605. In thisembodiment, a nickel conductive film is formed by a sputtering methodusing a metal mask. The connection terminals 610 and 611 are formed topartially cover the electrode terminals.

An optical sensor is cut out in a laser scribing step. In thisembodiment, a laser light is irradiated to regions where the openingportions are formed along axes A 612 a to 612 d and regions that is atright angle to the axis A and where the sensor element is not formedalong axes B 613 a to 613 d in order to cut out the optical sensor.

The optical sensor can be formed through the foregoing steps.

According to this embodiment, the optical sensor can be formed on aninsulating substrate. A concave portion is formed in a side face of theoptical sensor, and a connection terminal can be formed in this region.Thus, an area for connection with a wiring board can be increased, themounting strength is also increased, and at the same time, the conditionof connection can be seen and confirmed visibly. Accordingly,reliability on process can be enhanced. Only an opening portion and aconductive film are formed to form a connection terminal, and thus, aconnection terminal can be provided for every substrate. Therefore, itis possible to increase throughput in the step of forming a connectionterminal, and to mass-produce.

Embodiment 2

Various electronic apparatuses can be manufactured by incorporating asemiconductor device obtained according to the present invention. Suchelectronic apparatuses include a portable telephone, a laptop personalcomputer, a digital camera, a gaming machine, a car navigation, aportable audio equipment, a handy AV equipment, a film camera, aninstant camera, a room air-conditioner, a car air-conditioner, aventilating and air conditioning equipment, an electric pot, a CRT typeprojection TV, a lighting equipment, lightning facilities and the like.Specific examples of the electronic devices are shown hereinafter.

An optical sensor of the present invention can be used in a portabletelephone, a laptop personal computer, a digital camera, a gamingmachine, a car navigation, a portable audio equipment and the like as asensor for optimally adjusting brightness of a display and a backlightilluminance, and a sensor for saving a battery. A solar battery can beprovided for these electronic devices as a battery. The semiconductordevices can be downsized and highly integrated, and thus, electronicdevices can be more downsized by using them.

An optical sensor of the present invention can be mounted in anoperation switch of a portable telephone, and a handy AV equipment as asensor for controlling On and Off of a backlight LED and a cold cathodetube or a sensor for saving a battery. By being provided with a sensor,a switch is turned off in a bright environment, and battery consumptionby a button operation can be reduced for a long time. Becausesemiconductor devices according to the present invention can bedownsized and highly integrated, electronic apparatuses can be moredownsized and power consumption can be saved.

Further, an optical sensor of the present invention can be mounted in adigital camera, a film camera, and an instant camera as a sensor of aflash light dimmer control or a sensor for an aperture control. Inaddition, a solar battery can be provided for these electronic devicesas a battery. The semiconductor devices can be downsized and highlyintegrated, and thus, electronic devices can be more downsized by usingthem.

Moreover, an optical sensor of the present invention can be mounted in aroom air-conditioner, a car air-conditioner, and a ventilating and airconditioning equipment as a sensor for controlling airflow ortemperature. Because semiconductor devices according to the presentinvention can be downsized and highly integrated, electronic devices canbe more downsized and power consumption can be saved.

An optical sensor of the present invention can be mounted in an electricpot as a sensor for controlling a temperature for keeping warm. After anindoor light is turned off, the temperature for keeping warm can be setlow by the optical sensor of the present invention. Since the opticalsensor is small and thin, it can be loaded at a desired position.Consequently, saving electric power can be achieved.

An optical sensor of the present invention can be mounted in a displayof a CRT type projection TV as a sensor for adjusting a position of ascanning line (positioning of RGB scanning lines (Digital AutoConvergence)). Since the semiconductor device of the present inventioncan be downsized and highly integrated, the electronic device can bemore downsized by using it and be provided with a sensor at a desiredposition. In addition, high-speed automatic control of the CRT typeprojection TV is possible.

An optical sensor of the present invention can be mounted in variousdomestic lightning equipment, an outdoor lamp, a street light, anunmanned public utility, an athletic field, a car, a calculator and thelike as a sensor for controlling On and Off of various lightningequipment and lightning facilities. Electricity consumption can be savedby the sensor of the present invention. A battery can be downsized andthinned to downsize an electronic device by providing a solar batteryaccording to the present invention for such electronic devices as abattery.

This application is based on Japanese Patent Application serial no.2003-347676 filed in Japan Patent Office on Oct. 6, 2003, the contentsof which are hereby incorporated by reference.

1. A semiconductor device comprising: a thin film transistor formed overan insulating substrate, comprising: a semiconductor film having atleast a source region and a drain region; a gate insulating film; and agate electrode, wherein the gate insulating film is interposed betweenthe semiconductor film and the gate electrode, a semiconductor elementelectrically connected to one of the source region and the drain region;and a conductive film that is electrically connected to thesemiconductor element, wherein the semiconductor device has a concaveportion in a side face thereof, and wherein the conductive film isformed in the concave portion.
 2. A device according to claim 1, whereinthe conductive film is formed in a side face of the insulating filmcovering the semiconductor element and on a top face thereof.
 3. Adevice according to claim 1, wherein an area of the insulating substrateand an area for forming the semiconductor element are approximatelyequal.
 4. A device according to claim 1, wherein the concave portion hasone of a curved surface and a flat surface.
 5. A device according toclaim 1, wherein the concave portion has a curved surface and a flatsurface.
 6. A device according to claim 1, wherein the semiconductorelement has a semiconductor thin film.
 7. A device according to claim 1,wherein the conductive film is formed from an element selected fromnickel, copper, zinc, palladium, silver, tin, platinum and gold, and analloy containing the element.
 8. A device according to claim 1, whereinthe insulating substrate is heat-resistant.
 9. A device according toclaim 1, wherein the insulating substrate is light-transmitting.
 10. Adevice according to claim 1, wherein the insulating substrate is formedfrom one of plastic, glass and organic resin.
 11. A device according toclaim 1, wherein the semiconductor element has one of a thin filmtransistor and a diode.
 12. A device according to claim 1, wherein thesemiconductor element has a thin film transistor and a diode.
 13. Adevice according to claim 1, wherein the semiconductor element is anintegrated circuit having at least one of an optical sensor, aphotoelectric conversion device, a solar battery, and a TFT.
 14. Adevice according to claim 1, wherein the semiconductor device isincorporated into a camera.
 15. A device according to claim 1, whereinthe semiconductor device is incorporated into a personal computer.
 16. Adevice according to claim 1, wherein the semiconductor device isincorporated into a portable information terminal.
 17. A semiconductordevice comprising: a semiconductor element formed over an insulatingsubstrate; an electrode terminal connected to the semiconductor element;and a connection terminal connected to the electrode terminal, whereinthe semiconductor device has a concave portion in a side face thereof,and wherein the connection terminal is in contact with the insulatingsubstrate and the semiconductor element in the concave portion.
 18. Adevice according to claim 17, wherein the connection terminal is formedin a side face of the insulating film covering the semiconductor elementand on a top face thereof.
 19. A device according to claim 17, whereinan area of the insulating substrate and an area for forming thesemiconductor element are approximately equal.
 20. A device according toclaim 17, wherein the concave portion has one of a curved surface and aflat surface.
 21. A device according to claim 17, wherein the concaveportion has a curved surface and a flat surface.
 22. A device accordingto claim 17, wherein the semiconductor element has a semiconductor thinfilm.
 23. A device according to claim 17, wherein at least one of theconductive film and the connection terminal is formed from an elementselected from nickel, copper, zinc, palladium, silver, tin, platinum andgold, and an alloy containing the element.
 24. A device according toclaim 17, wherein the insulating substrate is heat-resistant.
 25. Adevice according to claim 17, wherein the insulating substrate islight-transmitting.
 26. A device according to claim 17, wherein theinsulating substrate is formed from one of plastic, glass and organicresin.
 27. A device according to claim 17, wherein the semiconductorelement has one of a thin film transistor and a diode.
 28. A deviceaccording to claim 17, wherein the semiconductor element has a thin filmtransistor and a diode.
 29. A device according to claim 17, wherein thesemiconductor element is an integrated circuit having at least one of aphotoelectric conversion device, a solar battery, and a TFF.
 30. Adevice according to claim 17, wherein the semiconductor device isincorporated into a camera.
 31. A device according to claim 17, whereinthe semiconductor device is incorporated into a personal computer.
 32. Adevice according to claim 17, wherein the semiconductor device isincorporated into a portable information terminal.
 33. A semiconductordevice comprising: a semiconductor element formed over an insulatingsubstrate; an insulating film covering the semiconductor element; and aconductive film to be electrically connected to the semiconductorelement, wherein the semiconductor device has a concave portion in aside face thereof, and wherein the conductive film is formed in theconcave portion and covers side faces of the insulating substrate andthe insulating film.
 34. A device according to claim 33, wherein theconductive film is formed in a side face of the insulating film coveringthe semiconductor element and on a top face thereof.
 35. A deviceaccording to claim 33, wherein an area of the insulating substrate andan area for forming the semiconductor element are approximately equal.36. A device according to claim 33, wherein the concave portion has oneof a curved surface and a flat surface.
 37. A device according to claim33, wherein the concave portion has a curved surface and a flat surface.38. A device according to claim 33, wherein the semiconductor elementhas a semiconductor thin film.
 39. A device according to claim 33,wherein the conductive film is formed from an element selected fromnickel, copper, zinc, palladium, silver, tin, platinum and gold, and analloy containing the element.
 40. A device according to claim 33,wherein the insulating substrate is heat-resistant.
 41. A deviceaccording to claim 33, wherein the insulating substrate islight-transmitting.
 42. A device according to claim 33, wherein theinsulating substrate is formed from one of plastic, glass and organicresin.
 43. A device according to claim 33, wherein the semiconductorelement has one of a thin film transistor and a diode.
 44. A deviceaccording to claim 33, wherein the semiconductor element has a thin filmtransistor and a diode.
 45. A device according to claim 33, wherein thesemiconductor element is an integrated circuit having at least one of aphotoelectric conversion device, a solar battery, and a TFT.
 46. Adevice according to claim 33, wherein the semiconductor device isincorporated into a camera.
 47. A device according to claim 33, whereinthe semiconductor device is incorporated into a personal computer.
 48. Adevice according to claim 33, wherein the semiconductor device isincorporated into a portable information terminal.
 49. A semiconductordevice comprising: a semiconductor element formed over an insulatingsubstrate; an electrode terminal to be connected to the semiconductorelement; an insulating film covering the semiconductor element and theelectrode terminal; and a connection terminal to be connected to theelectrode terminal through the insulating film, wherein thesemiconductor device has a concave portion in a side face thereof, andwherein the connection terminal is in contact with side faces of theinsulating substrate, the semiconductor element, and the insulating filmin the concave portion.
 50. A device according to claim 49, wherein theconnection terminal is formed in a side face of the insulating filmcovering the semiconductor element and on a top face thereof.
 51. Adevice according to claim 49, wherein an area of the insulatingsubstrate and an area for forming the semiconductor element areapproximately equal.
 52. A device according to claim 49, wherein theconcave portion has one of a curved surface and a flat surface.
 53. Adevice according to claim 49, wherein the concave portion has a curvedsurface and a flat surface.
 54. A device according to claim 49, whereinthe semiconductor element has a semiconductor thin film.
 55. A deviceaccording to claim 49, wherein at least one of the conductive film andthe connection terminal is formed from an element selected from nickel,copper, zinc, palladium, silver, tin, platinum and gold, and an alloycontaining the element.
 56. A device according to claim 49, wherein theinsulating substrate is heat-resistant.
 57. A device according to claim49, wherein the insulating substrate is light-transmitting.
 58. A deviceaccording to claim 49, wherein the insulating substrate is formed fromone of plastic, glass and organic resin.
 59. A device according to claim49, wherein the semiconductor element has one of a thin film transistorand a diode.
 60. A device according to claim 49, wherein thesemiconductor element has a thin film transistor and a diode.
 61. Adevice according to claim 49, wherein the semiconductor element is anintegrated circuit having at least one of a photoelectric conversiondevice, a solar battery, and a TFT.
 62. A device according to claim 49,wherein the semiconductor device is incorporated into a camera.
 63. Adevice according to claim 49, wherein the semiconductor device isincorporated into a personal computer.
 64. A device according to claim49, wherein the semiconductor device is incorporated into a portableinformation terminal.
 65. A semiconductor device comprising: asemiconductor element formed over an insulating substrate; and aconductive film that is electrically connected to the semiconductorelement, wherein the semiconductor device has a concave portion in aside face thereof, wherein the conductive film is formed in the concaveportion, and wherein a side surface of the insulating substrate has atapered shape.
 66. A device according to claim 65, wherein theconductive film is formed in a side face of an insulating film coveringthe semiconductor element and on a top face thereof.
 67. A deviceaccording to claim 65, wherein an area of the insulating substrate andan area for forming the semiconductor element are approximately equal.68. A device according to claim 65, wherein the concave portion has oneof a curved surface and a flat surface.
 69. A device according to claim65, wherein the concave portion has a curved surface and a flat surface.70. A device according to claim 65, wherein the semiconductor elementhas a semiconductor thin film.
 71. A device according to claim 65,wherein the conductive film is formed from an element selected fromnickel, copper, zinc, palladium, silver, tin, platinum and gold, and analloy containing the element.
 72. A device according to claim 65,wherein the insulating substrate is heat-resistant.
 73. A deviceaccording to claim 65, wherein the insulating substrate islight-transmitting.
 74. A device according to claim 65, wherein theinsulating substrate is formed from one of plastic, glass and organicresin.
 75. A device according to claim 65, wherein the semiconductorelement has one of a thin film transistor and a diode.
 76. A deviceaccording to claim 65, wherein the semiconductor element has a thin filmtransistor and a diode.
 77. A device according to claim 65, wherein thesemiconductor element is an integrated circuit having at least one of aphotoelectric conversion device, a solar battery, and a TFT.
 78. Adevice according to claim 65, wherein the semiconductor device isincorporated into a camera.
 79. A device according to claim 65, whereinthe semiconductor device is incorporated into a personal computer.
 80. Adevice according to claim 65, wherein the semiconductor device isincorporated into a portable information terminal.
 81. A deviceaccording to claim 1, wherein the semiconductor element is an opticalsensor.
 82. A device according to claim 17, wherein the semiconductorelement is an optical sensor.
 83. A device according to claim 33,wherein the semiconductor element is an optical sensor.
 84. A deviceaccording to claim 49, wherein the semiconductor element is an opticalsensor.
 85. A device according to claim 65, wherein the semiconductorelement is an optical sensor.
 86. A semiconductor device comprising: athin film transistor formed over an insulating substrate, comprising: asemiconductor film having at least a source region and a drain region; agate insulating film; and a gate electrode, wherein the gate insulatingfilm is interposed between the semiconductor film and the gateelectrode, a semiconductor element comprising a first electrode, alight-receiving portion and a second electrode; and a conductive filmthat is electrically connected to the semiconductor element, wherein thesemiconductor device has a concave portion in a side face thereof,wherein the conductive film is formed in the concave portion, andwherein the first electrode is electrically connected to one of thesource region and the drain region.
 87. A device according to claim 86,wherein the conductive film is formed in a side face of an insulatingfilm covering the semiconductor element and on a top face thereof.
 88. Adevice according to claim 86, wherein an area of the insulatingsubstrate and an area for forming the semiconductor element areapproximately equal.
 89. A device according to claim 86, wherein theconcave portion has one of a curved surface and a flat surface.
 90. Adevice according to claim 86, wherein the concave portion has a curvedsurface and a flat surface.
 91. A device according to claim 86, whereinthe semiconductor element has a semiconductor thin film.
 92. A deviceaccording to claim 86, wherein the conductive film is formed from anelement selected from nickel, copper, zinc, palladium, silver, tin,platinum and gold, and an alloy containing the element.
 93. A deviceaccording to claim 86, wherein the insulating substrate isheat-resistant.
 94. A device according to claim 86, wherein theinsulating substrate is light-transmitting.
 95. A device according toclaim 86, wherein the insulating substrate is formed from one ofplastic, glass and organic resin.
 96. A device according to claim 86,wherein the semiconductor element has one of a thin film transistor anda diode.
 97. A device according to claim 86, wherein the semiconductorelement has a thin film transistor and a diode.
 98. A device accordingto claim 86, wherein the semiconductor element is an optical sensor. 99.A device according to claim 86, wherein the semiconductor element is anintegrated circuit having at least one of a photoelectric conversiondevice, a solar battery, and a TFT.
 100. A device according to claim 86,wherein the semiconductor device is incorporated into a camera.
 101. Adevice according to claim 86, wherein the semiconductor device isincorporated into a personal computer.
 102. A device according to claim86, wherein the semiconductor device is incorporated into a portableinformation terminal.
 103. A semiconductor device comprising: a thinfilm transistor formed over an insulating substrate, comprising: asemiconductor film having at least a source region and a drain region; agate insulating film; and a gate electrode, wherein the gate insulatingfilm is interposed between the semiconductor film and the gateelectrode, a semiconductor element comprising a first electrode, alight-receiving portion and a second electrode; and a conductive filmthat is electrically connected to the semiconductor element, wherein thesemiconductor device has a concave portion in a side face thereof,wherein the conductive film is formed in the concave portion, whereinthe first electrode is electrically connected to one of the sourceregion and the drain region, and wherein the first electrode comprises alight-transmitting conductive film.
 104. A device according to claim103, wherein the conductive film is formed in a side face of aninsulating film covering the semiconductor element and on a top facethereof.
 105. A device according to claim 103, wherein an area of theinsulating substrate and an area for forming the semiconductor elementare approximately equal.
 106. A device according to claim 103, whereinthe concave portion has one of a curved surface and a flat surface. 107.A device according to claim 103, wherein the concave portion has acurved surface and a flat surface.
 108. A device according to claim 103,wherein the semiconductor element has a semiconductor thin film.
 109. Adevice according to claim 103, wherein the conductive film is formedfrom an element selected from nickel, copper, zinc, palladium, silver,tin, platinum and gold, and an alloy containing the element.
 110. Adevice according to claim 103, wherein the insulating substrate isheat-resistant.
 111. A device according to claim 103, wherein theinsulating substrate is light-transmitting.
 112. A device according toclaim 103, wherein the insulating substrate is formed from one ofplastic, glass and organic resin.
 113. A device according to claim 103,wherein the semiconductor element has one of a thin film transistor anda diode.
 114. A device according to claim 103, wherein the semiconductorelement has a thin film transistor and a diode.
 115. A device accordingto claim 103, wherein the semiconductor element is an optical sensor.116. A device according to claim 103, wherein the semiconductor elementis an integrated circuit having at least one of a photoelectricconversion device, a solar battery, and a TFT.
 117. A device accordingto claim 103, wherein the semiconductor device is incorporated into acamera.
 118. A device according to claim 103, wherein the semiconductordevice is incorporated into a personal computer.
 119. A device accordingto claim 103, wherein the semiconductor device is incorporated into aportable information terminal.